Antipsychotics for the treatment of schizophrenia: likelihood to be helped or harmed, understanding proximal and distal benefits and risks.

Benefit-risk decisions are the central part of the philosophy of evidence-based medicine. Although number needed to treat (NNT) and number needed to harm (NNH) can quantify differences between two antipsychotics in terms of benefits and risks for the treatment of schizophrenia, these benefits and risks can take on greatly differing degrees of importance or relevance depending on the subjective point of view of the patient and clinician, baseline risks, severity of the underlying illness, as well as the time horizon when these effects emerge. The metric of likelihood to be helped or harmed, the ratio NNH to NNT, can be helpful in quantifying the benefit:risk ratio, provided that the outcomes are carefully matched in terms of both importance to the clinician and the patient and whether they are proximal or distal. The examples provided are extensions to the initially published NNT and NNH analyses conducted by the first author.